[C:1]([NH:8][OH:9])([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].[OH-].[K+].[CH2:12]([O:14][C:15](=[O:20])[C:16](Br)([CH3:18])[CH3:17])[CH3:13]>C(O)C>[CH2:12]([O:14][C:15](=[O:20])[C:16]([O:9][NH:8][C:1]([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2])([CH3:18])[CH3:17])[CH3:13]To a solution of N-Boc-hydroxylamine (5.2 g, 39.05 mmol) in ethanol (100 mL) was added potassium hydroxide (2.63 g, 46.86 mmol), the mixture stirred at room temperature until a solution was formed. 2-Bromoisobutyric acid ethyl ester (6.87 mL, 46.9 mmol) was added and the reaction mixture heated at reflux for 18 hours. The reaction mixture was cooled to room temperature then filtered, and the filtrate was concentrated in vacuo. The resultant oily residue was partitioned between water (75 mL) and diethyl ether and the aqueous fraction was extracted with diethyl ether (2×100 mL). The combined organic extracts were dried (Na2SO4), filtered and concentrated in vacuo to give the title compound as a clear oil (9.5 g, 99%). LCMS (method C): RT=2.55 min, [M+H]+=248. 1H NMR (CDCl3, 400 MHz) 4.20 (q, 2H), 1.50 (s, 6H), 1.49 (s, 9H), 1.30 (t, 3H).
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